Recent studies have shown that many people use herbal therapies. Herbal products have been associated with organ dysfunction and unintentional over:lose. Although subjects enrolled in National Institutes of Health (NIH) research protocols may disclose their use of herbal remedies, the incidence and specific types of herbs used are not known and have not been systematically assessed. Concerns related to the toxicity profiles of the herbal remedies, as well as their unknown potential to confound research results, warrant further assessment of herb use in patients at the NIH. This study seeks to identify and characterize the current use of herbal therapies among 500 subjects participating in National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Child Health and Human Development, and National Institute of Arthritis and Musculoskeletal and Skin Diseases ambulatory care research protocols.